1. Field of the Invention
The present invention relates to a water-soluble ginger root extract substantially free of gingerols.
2. Description of the related art
A ginger root is a root of Zingiber officinale Roscoe belonging to the Zingiberaceae plant family. It is a crude drug used for long years as a stomachic. The extract of this ginger root has also been used as a material for cosmetics because of its hair growth promoting and antipruritic actions. In “The Japanese Cosmetic Ingredients Codex”, “ginger root extract” and “oil-soluble ginger root extract” are listed, while in “The Japanese Standards of Cosmetic Ingredients”, “ginger root tincture” is listed.
As main ingredients of a ginger root, essential oil ingredients such as zingiberone and zingiberene, and pungent and stimulating ingredients such as gingerols (for example, 6-gingerol, 8-gingerol and 10-gingerol) are known. Because of its action derived from the latter ingredients, a ginger root has been incorporated in a hair tonic or the like to improve the blood flow. There is a report (“Natural Medicine, 40, 333-339 (1986)”) that gingerols can satisfy the conditions as an indicator component of a ginger root. The existing “ginger root extract” and “oil-soluble ginger root extract” need a confirmation test by thin-layer chromatography, while the “ginger root tincture” needs “pungency” as its properties.
Gingerols have a strong skin irritating property so that an upper limit on their content is determined. “The Japanese Cosmetic Ingredients Codex” of Health and Welfare Ministry specifically limits the total amount of ginger root extract, oil soluble ginger root extract, ginger root tincture, capsicum tincture and cantharides tincture to 1% or less.
An object of the present invention is to provide a novel ginger root extract which is, different from the conventional one, substantially free of gingerols serving as a stimulant or pungent ingredient.